1. Field of the Invention
This invention relates to an image reproducing method and apparatus for reproducing a visible image with a first image reproducing means and reproducing a visible image with a second image reproducing means, which is of the same kind as the first image reproducing means or of a kind different from the first image reproducing means.
2. Description of the Prior Art
Heretofore, in cases where an image is displayed on an image displaying means, such as a CRT display device or a liquid crystal displaying device, a gradation converting table for converting the gradation characteristics of the image displaying means (i.e., the relationship between the image signal value and the logarithmic value of the luminance, or the like, on the image displaying means) into linear characteristics is prepared. Image processing is then carried out on the image signal and in accordance with the gradation converting table. A visible image, which is represented by the image signal having been obtained from the image processing, is displayed on the image displaying means. Also, in a system for displaying a radiation image, or the like, a visible image is firstly reproduced from an image signal representing an image and is displayed on an image displaying means. The visible image displayed on the image displaying means is viewed, and ultimate image processing conditions, under which the image signal is to be processed, are thereby adjusted. Image processing is then carried out on the image signal and under the adjusted image processing conditions, and a visible image is reproduced from the processed image signal and recorded on a recording material, such as film, with a recording means, such as a laser printer.
However, the gradation on the image displaying means and the gradation on the recording means do not perfectly coincide with each other. Also, the capacity of expressing an image is substantially different between the image displaying means and the recording material. Therefore, even if the image processing conditions appropriate for the image displayed on the image displaying means are adjusted, the adjusted image processing conditions will not necessarily be appropriate for the image, which is to be recorded on the recording material. In such cases, if the image is recorded on the recording material by being processed under the image processing conditions, which have been adjusted for the image displayed on the image displaying means, the problems will occur in that a desired level of gradation cannot be obtained, and in that the image recorded on the recording material becomes difficult to view.
It is also considered that the same problems as those with regard to the difference in gradation will occur also for the image sharpness expressed on the image displaying means and the image sharpness expressed on the recording material with the recording means.
Specifically, in cases where there is a difference in resolving power between the image displaying means and the recording means, a difference in sharpness in proportion to the difference in resolving power occurs between the image reproduced by the image displaying means and the recording means. Therefore, also for the image sharpness, the image processing conditions appropriate for the image, which is displayed on the image displaying means, and the image processing conditions appropriate for the image, which is to be recorded on the recording material by the recording means, do not necessarily coincide with each other.
The problems described above occur between the two different kinds of image reproducing means, i.e., between the image displaying means and the recording means. The same problems also occur between two image reproducing means, which are of the same kind. Specifically, in cases where the two image reproducing means are the image displaying means, such as the CRT display devices, it often occurs that the number of the scanning lines is different between the two image displaying means. It also occurs that one of the two image displaying means is a new one, and the other is the one, in which the light emission efficiency of the fluorescent screen has deteriorated with the passage of time or in which a change has occurred in the beam spot of the electron beam. In such cases, even if visible images are reproduced from the processed image signals, which have been obtained by carrying out the image processing under the same image processing conditions, visible images having the same level of gradation and the same level of sharpness cannot be reproduced on the two image displaying means.
Further, in cases where the two image reproducing means are the image recording means, such as laser printers, the problems will often occur in that a difference in image quality of the image, which can be expressed, occurs due to a difference in the number of scanning lines between the two image recording means, or the like.